Stress effect on lattice thermal conductivity of anode material NiNb2O6 for lithium-ion batteries

The thermal transport properties of NiNb2O6 as anode material for lithium-ion battery and the effect of strain were studied by machine learning interatomic potential combined with Boltzmann transport equation.The results show that the lattice thermal conductivity of NiNb2O6 along the three crystal directions[100],[010],and[001]are 0.947 W·m-1.K-1,0.727 W·m-1·K-1,and 0.465 W m-1·K-1,respectively,indicating the anisotropy of the lattice thermal conductivity of NiNb2O6.This anisotropy of the lattice thermal conductivity stems from the significant difference of phonon group ve-locities in different crystal directions of NiNb2O6.When the tensile strain is applied along the[001]crystal direction,the lattice thermal conductivity in all three directions decreases.However,when the compressive strain is applied,the lattice thermal conductivity in the[100]and[010]crystal directions is increased,while the lattice thermal conductivity in the[001]crystal direction is abnormally reduced due to the significant inhibition of compressive strain on the group velocity.These indicate that the anisotropy of thermal conductivity of NiNb2O6 can be enhanced by the compressive strain,and reduced by the tensile strain.